Leetcode 115: Distinct Subsequences (recursive)

leetcode_115a.cpp

#include <iostream>
#include <string>

using namespace std;

void match(const string& s, const string& t, int idxs, int idxt, int& matches) {
    if (idxt == t.size()) {
        matches++;
        return;
    }
    if (idxs == s.size()) return;
    for (int i=idxs; i<s.size(); ++i) {
        if (s[i] == t[idxt]) match(s, t, i+1, idxt+1, matches);
    }
}

int numDistinct(string s, string t) {
    if (s=="" || t=="") return 0;
    int matches = 0;
    match(s, t, 0, 0, matches);
    return matches;
}

int main() {
    //string s="babgbag"; //"rabbbit";
    //string t="bag"; //"rabbit";
    string s="adbdadeecadeadeccaeaabdabdbcdabddddabcaaadbabaaedeeddeaeebcdeabcaaaeeaeeabcddcebddebeebedaecccbdcbcedbdaeaedcdebeecdaaedaacadbdccabddaddacdddc";
    string t="bcddceeeebecbc";
    cout << numDistinct(s, t) << "\n";
    return 0;
}

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